A touch detection device and a touch panel, which are configured to detect a touch operation performed by a user with respect to a touch detection surface, are provided in, for example, a portable communication terminal such as a smartphone and a tablet terminal, and an information processing apparatus that is installed in stores so as to provide services corresponding to operations performed by customers.
In such a touch detection device and touch panel, a capacitive method is known as a method of detecting a touch operation performed by a user. The capacitive method is a method of detecting the touch operation by arranging a plurality of electrodes along the touch detection surface, and detecting a change in capacitance between the electrodes caused by approach of, for example, a finger of the user.
Japanese Patent Application Laid-open No. 2010-61351 discloses an information input apparatus that determines, based on a timing at which an integrated amount of currents generated during the touch detection reaches a predetermined value, whether the touch is performed with use of a finger or a stylus pen, relating to a technology of performing touch detection by the capacitive method.
In the capacitive method, the touch operation is detected based on the magnitude of the amplitude of a signal representing the integrated amount of currents, but the signal amplitude may vary due to noise. Therefore, when a configuration for detecting the operation is provided to, for example, a display device, false detection may occur due to display noise caused by a display element provided nearby.
Further, when determining whether the detected touch operation is performed with use of a stylus pen or a finger (stylus pen/finger determination), the determination is made based on, for example, an area of a region in which the touch operation is detected. However, in the case of such a method, incorrect determination may be made, such as an operation using only a leading end portion of the finger is determined as an operation using a stylus pen.
The present invention has been made in view of the above-mentioned problems, and has an object to provide a touch detection device, a touch panel, and an image display device that are less affected by noise and are capable of executing stylus pen/finger determination with higher accuracy.